The display modes of display devices include twisted nematic (TN), vertical alignment (VA), in-plane switching (IPS), fringe field switching (FFS), etc. Pixel structures usually adopt different storage capacitor structures according to different modes. For instance, the TN mode and the VA mode generally adopt the structure in which a storage capacitor is provided between a common electrode line and a pixel electrode. The IPS mode and the FFS mode generally adopt the structure in which a storage capacitor is formed between a common electrode and a pixel electrode. The structure of the storage capacitor affects the stability of pixel voltage and hence directly affects the quality and the yield of a display.